It is well known in the medical arts that the treatment of certain physical conditions benefits markedly by the application of pressure to a body extremity such as an arm or a leg in a manner to promote the flow of a body fluid within the same from a distal portion thereof toward a proximal portion thereof. For example, the affliction known as Park-Weber Syndrome often may cause a limb of the afflicted to swell to a size much greater than normal size as lymphatic fluid accumulates in the limb. One prior mode of treatment for this affliction has been a double walled sheath or stocking in which air pressure is introduced between the walls to squeeze the limb. It has been found that this and other such systems which rely on uniform pressure application throughout the length of the afflicted limb do not perform very well and in fact may interfere with the desired distal-to-proximal flow of lymphatic fluid.
Other approaches to treatment of Park-Weber syndrome are disclosed as a sheath that is separated into a number of longitudinally spaced inflatable air cells encircling the limb to be treated. These cells are inflated by uniform air pressure successively from the distal end to the proximal end of the sheath with the intent of promoting fluid flow in the desired direction. However, many of these systems too have been ineffectual as they rely on pressure being maintained at the same level in all the pressurized cells. U.S. Pat. Nos. 2,533,504 and 2,781,041 disclose examples of such systems.
My prior U.S. Pat. No. 4,370,975 discloses an apparatus for treating Park-Weber Syndrome and similar afflictions through the use of a multi-cell sheath which encompasses the swollen limb. Pressure is applied in the cells of the sheath in timed sequence from the distal-most cell to the proximal-most cell, the sequence of pressures applied also defining a decreasing gradient pressure from a maximum pressure applied in the distal-most cell to a minimum pressure applied in the proximal-cell when all of the cells are pressurized. Generally, for each pair of adjacent cells, the more distal of the pair has applied therein a higher pressure than the more proximal of the pair. This application of pressure from distal to proximal cells in timed sequence, as described, comprises a cycle, and such cycle may be repeated indefinitely.
Prior to introduction of the technology disclosed by my cited prior patent, the art did not contemplate such a pressure gradient from cell to cell in an inflatable appliance, and therefore no need for precise and uniform adjustment of the cell-to-cell pressure differential had been recognized. Such need has now become apparent as it appears in many instances the pressure gradient from one cell to the next, that is the pressure differential therebetween, should remain uniform with only the magnitudes of the various cell pressures being varied, in a uniform manner, to adapt the treatment for a particular patient. This being the case, I have invented a pressure adjustment apparatus for use in such a system which permits adjustment of the magnitude of air pressure delivered to the respective cells of a multi-cell inflatable apparatus while maintaining a uniform pressure differential between any given pair of cells. That is to say, the pressure differential between a given pair of cells remains constant as pressure adjustments are made. The pressure differential between other pairs of adjacent cells may differ from that for such a given cell, but these too will remain constant during cell pressure adjustments.
Clearly, the pressure adjustment apparatus should offer not only this uniform adjusting capability, but in addition the option for adjusting the cell-to-cell pressure differential when desired, as well as a simple and quickly performed pressure adjustment procedure to simplify operation of the apparatus and thereby reduce requirements for direct supervision by an attending physician.